This invention relates to an outboard motor with an engine tachometer and more particularly to an improved, simplified tachometer mounting and driving arrangement for an outboard motor.
Outboard motors, as with many applications wherein internal combustion engines are utilized as the driving media, can benefit by the provision of a device wherein the operator can monitor the speed of the engine. Monitoring engine speed has a number of known advantages. For this reason, the provision of a tachometer is frequently resorted to so as to permit the operator to monitor the engine speed.
With an outboard motor, on the other hand, it is somewhat difficult to provide a tachometer for measuring engine speed. The outboard motor normally includes a power head in which the internal combustion engine is contained. This engine is encircled by a protective cowling. Thus, if a tachometer is employed, some arrangement must be provided for conveying the engine speed signal from the engine externally through the cowling to an indicator device that is positioned in proximity to the operator. With mechanically driven tachometers, the disadvantages are obvious. The same is true with conventional electrical-type tachometers due to the fact that the cowling must be readily removable for servicing. In addition, the engine normally is free to vibrate relative to the cowling and this vibration, with systems of the the type heretofore proposed, has placed stress on the transmitting device (such as the wires) that can cause failures.
Devices have been proposed wherein the engine speed indicator is mounted on the protective cowling and is not directly driven by the engine. For example, U.S. Pat. No. 2,649,848, entitled "Speed Indicating Device For Outboard Motors", issued in the name of D. A. Armstrong on Aug. 25, 1953 shows an arrangement wherein the speed is indicated by a vibrating indicator. In a somewhat similar vein, U.S. Pat. No. 2,798,472, entitled "Engine Tachometer", issued in the name of D. A. Armstrong on July 9, 1957 shows a magnetic type of device. Although in principle these devices are meritorious, they do not provide a true indication of actual engine speed and are not sufficiently accurate.
It is, therefore, a principle object of this invention, to provide an improved outboard motor with an engine tachometer.
It is another object of this invention to provide an improved speed indicating device for an outboard motor that will provide a highly accurate and yet trouble free operation.
It is a further object of this invention to provide an engine tachometer for an outboard motor that is wholly supported by the engine cowling but which nevertheless provides an accurate indication of engine speed.